Color thermal printers with a small roller platen use a dye donor and a dye receiver positioned between a print head and the platen for printing information upon the dye receiver. A printing operation typically begins with a loading sequence in which the print head and dye donor are spaced away from the roller platen, and the dye receiver is moved from a supply tray along a receiver transport path defined by a receiver transport mechanism. The receiver transport mechanism urges the dye receiver toward a gap between the print head and the roller platen. After moving through the gap, the dye receiver is positioned appropriately and a printing sequence occurs where information is printed on the dye receiver.
A problem occurs during the loading sequence as the dye receiver initially approaches the gap between the print head and the platen. The stiffness of the dye receiver can cause it to engage the dye donor upstream of the gap, instead of passing through the gap without touching the dye donor. The friction from the dye receiver engaging the dye donor requires greater drive forces to move the dye receiver through the gap than would otherwise be necessary.
One method to overcome this problem is to increase the power or complexity of the receiver transport mechanism, incurring the disadvantages of increased cost and complexity.
Another method to overcome this problem is to space the print head and dye donor a larger distance from the roller platen during the loading sequence. This has the disadvantages of increasing the printer's volume and print operation time.
Yet another method to solve this problem is provided by this invention, in which the dye donor is moved in the same direction as the dye receiver during the loading sequence to reduce friction between the dye donor and dye receiver. When the dye receiver has passed through the gap, the dye donor is moved in a reverse direction to rewind it and thus minimize unused dye donor.